In this project we propose to examine the effects of short- and long-term microwave (MR) and cold exposure of neuroendocrine and central opiocortin neuropeptides. The work is predicated on the hypothesis that central opiocortin systems are involved in organizing the efferent hypothalamic neuroendocrine responses which are evoked by these 2 stressors. The effects of cold exposure are compared with those of MR because it also has well characterized endocrine responses and involves thermoregulatory mechanisms. Plasma levels of corticosterone, thyroxine, TSH, GH and Prolactin will be measured to monitor peripheral endocrine responses. The concentrations of ACTH (4.5K), Beta-endorphins (c,c, '-fragment and acetylated forms) as well as several precursors in hypothalamus, brainstem, and pituitary will be measured by a combination of fractionation techniques and radiommunoassay. The long-term objectives of this work are to understand (a) the mechanisms of response to and biological effects of MR and (b) the organization and functions of central opiocortin neuropeptides.